Preparative separation-purification systems using liquid chromatographs are used in pharmaceutical or similar fields for the purpose of collecting samples for storing various compounds obtained through chemical synthesis in the form of a library, or for analyzing the various compounds in detail. Systems described in Patent Document 1 and Patent Document 2 are known as some of such preparative separation-purification systems.
In such systems, target components (compounds) in a sample solution are temporally separated by a liquid chromatograph. Then, the separated target components are introduced into respective trap columns and temporarily captured therein. Subsequently, a solvent is flown through each trap column to elute the captured component from the trap column, whereby the solution containing the target component at a high concentration is collected in a container. Then, each collected solution is subjected to a vaporizing and drying process to remove the solvent and collect the target component in the form of solid.
The vaporizing and drying process is normally performed according to, for example, a method of heating or centrifuging the collected solution. In this case, it takes several hours or even days to perform this method. In order to find effective medicinal compounds from many synthetic compounds, especially in pharmaceutical fields, various improvements in efficiency have been attempted. For example, an analysis time is shortened by increasing the analysis speed of analytical instruments, or by optimizing analytical methods. However, the vaporizing and drying process is the longest process among all processes, and hence it is critical to shorten this process.
A method for solving this problem is disclosed in Patent Documents 3 to 6. The method involves dropping a solution containing a target component into a collection container while blowing air, nitrogen, or another kind of gas at the drops of the solution, and thus nebulizing the solution to assist vaporization by heating of the solvent.
A normal procedure of the vaporizing and drying process according to the method of Patent Documents 3 to 6 (hereinafter, referred to as “gas-blowing vaporizing and drying process”) is described with reference to FIGS. 9A-9D. A preparative separation-purification system is provided with a needle 50 having a triple-tube structure including a solution-introducing tube 50A, a gas-introducing tube 50B that encloses the solution-introducing tube 50A, and a washing-liquid-introducing tube 50C that encloses the gas-introducing tube 50B as illustrated in FIG. 9C. The inner of the introducing tubes 50A, 50B and 50C protrudes from the outer one. A collection container 53 housed in a temperature regulated block 54 is placed below the needle 50. The collection container 53 includes a collection container body 51 and a cap 52 to be fitted to the upper opening of the collection container body 51. The cap 52 includes two septa 52A and a doughnut-shaped cushion 52B sandwiched between the two septa 52A.
In this process, the needle 50 is moved downward, and passes through the central hole of the cushion 52B while penetrating through the septa 52A, until its tip come into the collection container 53. Along with this downward movement of the needle 50, an exhaust duct 55 is also moved downward, and is brought into tight contact with the cap 52 by means of the cushion 52B so as to cover the hole that is formed in the cap 52 by the needle 50. Subsequently, a solution and a gas are respectively introduced through the solution-introducing tube 50A and the gas-introducing tube 50B into the collection container 53.
After passing through the solution-introducing tube 50A, the solution is dropped from the tip of the needle 50 inserted into the collection container 53, and simultaneously, gas is ejected from the gas-introducing tube 50B provided outside of the solution-introducing tube 50A. By this gas flow from the gas-introducing tube 50B, the solution being dropped from the solution-introducing tube 50A is sheared into fine droplets (mist) and the droplets attach to the inner wall of the collection container 53. Since the collection container 53 is heated by the temperature regulated block 54 surrounding the container, the solvent in the fine droplets attached to the inner wall vaporizes, so that only the solute remains in the form of powder. The gas introduced into the collection container 53 and the vaporized solvent pass through the gap of the hole that is formed by the needle 50 penetrating through the cap 52, and then pass through the exhaust duct 55, to be discharged to the outside of the collection container 53.
In this gas-blowing vaporizing and drying process, the solute may deposit on the tip of the needle 50. As a result, the gas flow from the gas-introducing tube 50B may be changed, or part of the gas flow may be hindered, so that the shearing efficiency of the dropped solution may be decreased. In such a case, a washing liquid (normally, a solvent that has a strong eluting power and easily vaporizes, such as dichloromethane) is introduced through the washing-liquid-introducing tube 50C, to thereby wash the portion of the gas-introducing tube 50B protruding from the washing-liquid-introducing tube 50C and the portion of the solution-introducing tube 50A protruding from the gas-introducing tube 50B.